How to reliable detect a MacPorts-ported compiler?

[Jeffrey Walton]

> Again, I have to ask why you want to do this.

My apologies, I was not trying to be rude. I specifically avoided
addressing any of these questions because of the bikeshedding
involved.

> What problem are you seeing with FSF GCC compiled with MacPorts that you do not see with FSF GCC compiled on a Mac by some other means?

None that I am aware.

But that's not the problem I am trying to solve.

Jeff